The present disclosure relates to valve assemblies for opening or closing fluid paths. More particularly, the present disclosure relates to valve assemblies, such as check valves, adapted for use with plunger pumps for high temperature and high stress applications such as car washes, and the like.
Fluid pumps are often described by the type of motion used, displacement, mechanism, cylinders and pressure. For example, a reciprocating pump converts rotary driving motion from a motor, or the like, to a linear pumping motion with a pumping mechanism. Driving speed of the motor in revolutions per minute is often directly related to the output of the reciprocating pump. A reciprocating positive displacement pump first moves fluids into the pump, and then the fluids are moved out of the pump. Plunger pumps are reciprocating positive displacement pumps that displace a given amount of fluid on each cycle, or stroke, of the plunger. The reciprocating motion of the plunger, with check valves on each side of the pump body, creates the pumping action of the fluid. On the suction stroke, or up stroke, low pressure in the pump body closes a discharge, or outlet, check valve, opens a suction, or inlet, check valve, and pulls fluid into a pump cylinder in one example. On the discharge stroke, or down stroke, high pressure in the pump body closes the suction check valve, opens the discharge check valve, and pushes the fluid out of the pump cylinder in the example. Typically, these pumps include one to six cylinders. A simplex pump may only include one cylinder, but a more common configuration is a triplex pump with three cylinders. When pump forces fluid through a restriction in excess of about 150 pounds per square inch, the pump is often termed a high-pressure pump.
Plunger pumps include several advantages, and a few of these advantages are listed here. Plunger pumps provide a constant flow of fluid at high pressures over long periods of time, and they can operate without fluid allowing them to operate unattended. Also, plunger pumps are adapted to vary the amount of flow without having to vary the speed of the drive motor. Also, plunger pumps are durable and can operate in a variety of conditions. Several of the many applications of plunger pumps include septage and sludge, water treatment, desalination, and industrial cleaning such as car wash systems.
Car wash systems are a particularly useful and demanding application for plunger pumps. Plunger pumps in car wash systems are typically required to pump water at high temperatures, such as greater than approximately 165 degrees (about 74 degrees Celsius) Fahrenheit and often up to approximately 185 degrees Fahrenheit (about 85 degrees Celsius). These high temperatures sometimes cause premature damage to some of the internal components of the plunger pump, such as the check valves described above.
FIG. 1 shows an example of a prior art check valve assembly 10 that is provided here to illustrate how high temperatures sometimes cause premature damage. The check valve assembly 10 includes a housing 12 that surrounds and supports a spring-loaded valve mechanism 13. The check valve assembly 10 is adapted to permit fluid to flow through the housing 12 when the valve mechanism 13 is open. The valve mechanism 13 includes a spring 14 that biases a valve plate 15 against a valve seat 16. The housing includes a spring guide 17 that maintains the proper position of the spring 14 within the housing 12. The housing includes a first support ring 18 distal to the valve seat 16 and a second support ring 19 proximate to the valve seat 16. No more than four legs 20, are coupled to and extend between the support rings 18, 19. The legs 20 are spaced-apart around the support rings 18, 19. The legs 20 and support rings 18, 19 provide the structural integrity of the valve assembly and are referred to as the valve cage. A stop ring 21 is also included in the valve cage to prevent over-travel of the valve plate 15 and to define a fully open position of the check valve assembly 10. Water flows between the second support ring 19 and the valve plate 15 and in through a hole 22 in the valve seat.
The prior art check valve assembly 10 has proven itself effective in low temperature applications, but it has a tendency to develop stress fractures when used in high temperature applications. Specifically, the stress fractures typically occur on the second ring 19 in between the legs 20 as a result of high temperature applications and fluid cavitation.
Initial attempts to correct this problem have failed or have compromised the efficiency of the check valve assembly. For example, one proposed solution by those skilled in the art involved increasing the height of the second ring 19. This proposed solution failed to prevent stress fractures after testing. Further, the flow characteristics of the check valve assembly were adversely affected and reduced the fluid flow through the housing when the valve plate 15 was in an open position. Another proposed solution by those skilled in the art was to increase the width of each leg 20. This proposed solution also restricted flow of fluid through the check valve assembly as it narrowed the spacing between each leg.
Accordingly, there is a need for a reinforced check valve assembly that resists stress fractures as a result of high temperature applications and fluid cavitation, and that does not reduce fluid flow capacity. The check valve assembly should also be close enough to the external dimensions of existing check valve assemblies so as to be interchangeable in existing plunger pumps.